legal – Portfolio release for photographing children under 18?

I will photograph the events of a school and its students for a week. However, I am not sure that the standard publication of the portfolio will suffice given the age of the subjects.

Important background:

  • I am mainly there as a teacher, but I took the opportunity to build my portfolio because it is a new genre for me.
  • I have the verbal Go ahead from the event organizer, of course, but at the same time, since the kids will be between 13 and 14 years old, I wonder what I should do.
  • My intention is only to advertise my services, non-commercial, without defamation. However, they would not always be substantive members, some images would be group photos, candid moments, etc.

My best guess is that signing the publication by the event organizer should be easier than 60 or more children without a guardian, also because they travel from another continent. towards the EU. I imagine that the organizer of the event is responsible during their visit.